The use of peat as a growth medium for plants has been a mainstay of British horticulture for many years. However, the extraction of peat from peat bogs has come under increasing pressure from environmental groups who are concerned for the loss of these ecosystems. This has lead to a search for alternative growth media which is more environmentally acceptable. One alternative is to use coir, a waste by-product from the processing of coconuts which has hitherto been stored in large waste dumps in regions where coconuts are processed, eg. Sri Lanka.
Coir is compacted into bricks to reduce its volume for transport. The bricks are then disintegrated to the constituent dust by use of an appropriate mill. The coir at this stage often contains about 15% by weight of water. Before sale as a plant growth medium, the coir is usually hydrated to about 70% by contacting the coir with water. 90% of the total hydration occurs within a few minutes of contact with the water, the hydration being completed while the coir is stored for approximately 24 hours. The fully hydrated coir is then available for sale.
As the coir in the dumps has usually been stored in the open in tropical climates for a long time, often for many years, there is a danger that the coir may be contaminated by, for example, fecal matter which may contain harmful microorganisms, especially coliform bacteria. These microorganisms are potentially harmful both to plants grown in the coir and also to those handling the material, especially where there is intimate contact between the material and eg. the hands of a user as would be the case in normal gardening and horticultural activities. It is therefore expedient that the coir is disinfected to ameliorate these risks.
However, many common disinfectants when employed at effective concentrations leave residuals or toxic by-products in a growth medium such as coir which are phytotoxic to seeds or plants, for example methyl bromide or active chlorine compounds. Accordingly, it is an object of the present invention to provide a method for disinfecting coir.
It is a further object of the present invention to provide a method for disinfecting coir which ameliorates or eliminates the disadvantages of alternative disinfectants for coir that is intended as a plant growth medium.